Our research will continue to be devoted to the broad area of the conformational analysis of peptides, polypeptides and polydepsipeptides, with the aim of relating molecular structure to biological properties in peptidic biomolecules. We will concentrate our research specifically in several areas. Firstly, we will continue our work on the detailed conformational analysis of oligopeptides. We will use a combination of techniques, including nmr, CD and IR spectroscopy. Our nmr studies will concentrate on the application of double resonance, in conjunction with deuterium, 13C and 15N-labelled peptides and special deuterated solvents. This approach, together with the synthesis of oligopeptide series with sequential replacement of each residue by, for example, glycine, should result in complete assignment of resonances and give important conformational information. Secondly, we will be concerned with the conformations in solution of N-alkylated diketopiperazines. CD studies using the ultrathin cell we have developed, together with studies in the vapor phase and at low temperatures, should give conformational information about the diketopiperazine ring. Nmr studies will give complementary information about the preferred conformation of the side chains. Finally, we will extend our studies of polydepsipeptides such as poly(L-alanyl-L-alanyl-L-lactic acid). We have developed a theoretical approach to calculate the CD spectra of these compounds and also the thermodynamics of helix-coil transitions. Information we derive from these theoretical and experimental studies will give valuable information about the fundamental interactions which stabilize the polypeptide alpha-helix.